I have a denali with the 6.0. I love it but its a gas drinker. Sure the 8.1 is worse. Depends on what you are towing though. I don't tow very far and think our longest trip was 4 hours with the boat (209). Handled it fine.........wallet did not. To be honest I'm not sure I would need more than the 6.0 but I hated towing with my buddies 5.3